Process for the production of phosphorus and fusion cement from natural phosphates



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Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

WLADIMIR KYBER, OF BERLIN-STEGLITZ, GERMANY.

PROCESS FOR THE PRODUCTION OF PHOSPHORUS AND FUSION CEMENT FROM NATURAL PHOSPHATES.

No Drawing. Application tiled July 18, 1926, Serial No. 123,008, and in Germany August: 4, 1925.

The invention relates to a process for extracting phosphorus from natural phosphates in a more'rational, and at the same time more wonomically p acticable manner, and for obtaining it in a. suitable form.

"Wohlcr has made known the. rcactirm for extracting; phosphorus from natural phos phatcs by heating the latter with carbon and silicic acid. On this heating of the natural phosphate with carbon and silicic acid, a tri-silicate dross was left, which melted at a mmleratcly high tennierature, and which had no im'lustrial value. The process is un economical, in so far that a high temperature is necessary for fusion, and no useful byproduct results. lilorcm'cr, this process does not give a. good yield of phosphorus.

it. has also already been proposed to extract the phosphorus from calcium or aluminum phosphates without adding carbon, by mixing: the phosihates with clay and melting them in an e lectric furnace havinpan arc temperature of about 3000 ,3. (see American Patent No. 1.0Tti,-l-9T). This process also is uneconomical because of the great expenditure of heat energy.

Again, it has further been proposed to obtain )hosphorus in the form of phosphoric acid by sintering a mixture of natural phosphate of calcium and aluminium phosphate without the addition of carbon, and thereby obtaining together with the phosphorus a celnent'itlous productin the nature of an'aluminium-containing Portland cement.

Since in this process calcination is aticom.

panied by oxidation the phosphorus is obtained in the term 0 its oxide. (See American Patent No. 1,000,311). This process is uneconomical on account of the necessarily high temperatures required.

Finally, it has been proposed to extract the plies )horus from natural calcium phosphate, silicates and silicie-acid containing clay at a comparatively low temperature of about 1400 O. in the form of phosphorus )entoxide, b calcining such a mixture. ll ere the CO! ition of a low temperature of fusion is fulfilled, but the resultant dross is of less value and has atmost the. rahte ot? a lozzolana cement. (Sec American Patent No. 097,086).

The process oi. the present invention diti'ers" from the processes described above in that it is ctl'ected with the use of carbon as in the first-mentioned process of Wohlcr,

and by the increase of the quantity of alumina in the dross at the expense of lime and silicic acid, it not only makes a low temperature of fusion possible, but. also produces simultalwously a valuable 't'usion cement as dress. The quantity of alumina in the dross must be at least 27%, and the. charge must be proportioned correspondingly.

The. process will be further illustrated by two examples.

[t'a'om fle 1.

One. ton pebble, 0.0 ton bauxite, and 1.5 tons of coke are. smclted together. A fusion cement of the following composition results: Ca()==4-2.5%: A1,0,,=41.0%: SiO,-*=l6.5%.

Eaumnple' :3.

(lneton pebble phosphate to 1 ton natural aluminium phosphate, ton bauxite, and 3 tons colic. The material is crushed or if necessary ground and formed into briquettes and melted t'or rednct ion purposes in a. blast furnace. A 'l'usion ccnnxntv is producwl of approxinmtcly the following composition:

CaO 43.5% M 0, 40.5 SiO A phospliorus-contaiiiing iron regulus also results, and an elementary phosphorus-containing gas.

\Vit-h this carrying out of the process, cements of a high alumina content. result as dross, which cements are known technically as fusion cements. The high quantity of alumina can be secured, as will be seen from the examples, either by the addition of bauxite or by the employment of an aluminium phosphate together with calcium phosphate. It. is possible, moreowr, it alun1iniuni-phosphate only is used and calcimn phosphate is not available, to constitute the charge so that the lime necessary for the making of the cement is added in the form of'carbomlte of lime.

The present process can, however. be so carried. out, that instead of phosphoric acid. alkali phosphate is obtained directly from the process. For this l'nu'pose the charge for the furnace is so constituted that it contains alkali compounds. As alkali compounds there are available feldspar and cryolite, or

soda may be employed. It is, in this case, of no importance iwlth Which of the two above-described forms of carrying out the any other suitable compound oil potash or process one starts, whether from calcium phosphates with addition of aluminum compounds, or from aluminium phosphates with addition of lime compounds. In any case, the additions of the alkali compounds influence the molten mass very favourably, and

- at the temperature of fusion the alkalis become volatilized with the phosporus and combine with it under the influence of the carbonic acid into alkali phosphates, which are thus obtained in the same process with the fusion cement. The phosphprus is obtained in large quantities in the form of phosphates. According to the form of carrying out the process as described above, it

is possible to work in a blast furnace or' shaft furnace in such a mannerthat the generator gas produced is retained. Thereby the heat of the fuel is most economically utilized.

The process will be illustrated by an example with accompanying figures.

It should be observed that for the sake of simplicity that ashes content of the coke is left out of consideration in the figures given,

and that it is further assumed that all the Ziron of the charge is combined with phosphorus and passes over in the regulus as phosphite of iron, As crude material will be taken a pebble phosphate of the composition:

0.6 ton bauxite and 1.05 tons feldspar, and this mixture is sm'elted down in a blast furnace or shortened generator furnace, with the addition of the quantity of coke necessary for the heating. A dross of approximately the following composition is obtained:

J In this case the proportion of potassium oxide to phosphorus pentoxide is about 8%. This proportion is not essentially increased by the addition of feldspar-f Itis possible with the process to start from silicates of aluminum. There is then the advantage of carrying it out without the addition of bauxite, but 'in this case carbonate of lime must be added as a corrective. According as a high proportion of potassium to phosphorus pentoxide is desired, feldspar or chloride of potassium may be added to the mixture.

I claim:

1. The process for treating phosphates and recovering by-products which comprises smelt'irr together natural calcium phosphate, aluminium phosphate and carbon in such proportions that the dross contains at least 27% aluminium oxide.

2. The process for treating phosphates and recovering by-products which comprises smeltin a mixture including natural calcium phosphate, aluminous material and carbon in such proportions that the dross contains at'least 27 aluminium oxide.

3. The process for treating phosphates and recovering by-products which comprises smelting a mixture including natural calcium phosphate, bauxite and carbon in such proportions that the dross contains at least 27 aluminium oxide.

4. The process for treating phosphates and recovering by-products which comprises smelting a mixture including natural alumiminium phosphate, a compound of calcium, and carbon in such proportions that the dross contains at least 27 aluminium oxide.

5. The process for treatin phosphates and recovering by-products which comprises smelting a mixture of natural calcium phosphate, aluminium phosphate, coke and alkali compound in such proportions that the escaping phosphorus oxide combines with evaporated alkali and the resultant dross contains at least 27 aluminium oxide.

6. The process for treating phosphates and recovering by-products which comprises smelting a mixture of natural calcium phosphate, a compound of aluminium, an alkali compound and coke in such proportions that the escaping phosphorus oxide combines with evaporated alkali and the resultant dross contains at least 27% aluminium oxide. j

7. The process for treating-phosphates and recovering by-products which comprises smelting a mixture of natural phosphate, bauxite, an alkali compound, and coke in such proportions that the escaping phosphorus oxide combines with evaporated alkali and the resultant dross contains at least 27% aluminium oxide.

8. The process for treating phosphates and recovering by-productswhich comprises smelting a mlxture including natural' calcium phosphate, feldspar, an aluminum compound other than feldspar, and coke in such proportions that the escaping phosphorus oxide combines with evaporated alkali and the resultant dross contains at least 27 aluminium oxide.

9. The process for treating alkali phosphates and recovering by-products which comprises smelting a mixture including natural aluminum phosphate, a compound of calcium, an alkali compound and carbon in such proportions that the escaping phosphorus oxide combines with evaporated alkali and the dross contains at least 27% aluminium oxide.

- WLADILHR KYBER. 

